Release and blocking mechanism for power operated typewriters

ABSTRACT

A shift release mechanism is connected to an electrical switch and to a control knob on a power operated typewriter. Operating the control knob actuates the electrical switch from a closed state to an open state and actuates the shift release mechanism for releasing a shift keylever to cause a platen supporting carriage to move from an upper position to a lower position. The shift release mechanism further includes a finger positioned to block the depression of the shift keylever when the electrical switch is in the open state.

United States Patent [1 1 [111 3,920,114

Shattuck et al. 5] Nov. 18, 1975 RELEASE AND BLOCKING MECHANISM OTHERPUBLICATIONS F R POWE WR 0 R OPERATED TYPE ITERS IBM TechnicalDisclosure Bulletin, Vol. 4, No. 12,

[75] Inventors: Richard E. Shattuck; Albert H. M 1962 20 & 21

Cryder, both of Cortland, NY.

[73] Assignee: SCM Corporation, New York, NY. Primm'y Examiner paulShapiro D Attorney, Agent, or Firm-Milton M. Wolson, Esq.; [22] Filed:Sept. 9, 1974 Stanley Klem 21 Appl. No.: 504,413

[57] ABSTRACT A shift release mechanism is connected to anelectril97/lgziJl Cal Switch and to a Control knob on a power Operated[58] Fieid 80 107 12 typewriter. Operating the control knob actuates theelectrical switch from a closed state to an open state [56] ReferencesCited and actuates the shift release mechanism for releasing a shiftkeylever to cause a platen supporting carriage UNITED STATES PATENTS tomove from an upper position to a lower position.

2,304,357 12/1942 Helmond 197/80 The hift relea e mechanism furtherincludes a finger 2,499,053 2/1950 Bu chel r r r r 197/80 positioned toblock the depression of the key- 2,506,703 5/1950 Chisholm l97/107 leverwhen the electrical Switch is in the Open state 3,349,886 10/1967Madison et al. 197/107 3,572,488 3/1971 Kuramochi 197/80 X 6 Claims, 3Drawing Figures Sheet 1 of 2 U.S. Patent Nov. 18, 1975 U.S. Patent Nov.18, 1975 Sheet 2 of 2 3,920,114

RELEASE AND BLOCKING MECHANISM FOR POWER OPERATED TYPEWRITERS BACKGROUNDOF THE INVENTION The present invention relates to power operatedtypewriters and more particularly to a shift release and blockingmechanisms for a carriage shift control mechanism.

lnactivating various functions of a power operated typewriter, when thepower is turned off, to prevent damage to the mechanism or injury to theoperator has been recognized as a perennial concern within thetypewriter industry.

Shift release and blocking mechanism in the prior art have includedbails that were actuated by opening a switch. The bail conditioned allkeylevers to be inoperable but did not disengage any function keys thatwere already depressed. Consequently, when the switch was closed, thetyping function, that was actuated by the depressed function key,completed itscycle. In most cases, the added strain placed on the powersource by the completing function cycle combined with the strain ofbringing the typewriter mechanism to operation readiness could overloadand cause damage to the power source.-

In the event that the function selected was a carriage return functionand the operator was cleaning the typewriter, a sudden carriage returncycle could cause injury. 1

None of the prior art teaches a mechanism that releases a function keywhen the electrical switch is conditioned to an open state and rendersthe key inoperable until the switch is in a closed state.

SUMMARY OF THE INVENTION Briefly described, the present inventionteaches a shift release and blocking mechanism for a shift mechanism-ofa power operated typewriter. The shift mechanism includes a shiftkeylever and shift lock link. The shift lock link is pivotal on theshift keylever and includes an abutment having a recessthat engages afixed shelf when the shift lock link is actuated.

A control knob has a link extending in opposite directions therefrom.One end of the link is coupled to a switch mechanism in such a mannerthat rotation of the control knob results in a corresponding movement ofthe switch mechanism to render the switch circuit closed or opendepending on the direction of rotation of the control knob. The otherend of the link is coupled to a shift control mechanism that includes apivotal bellcrank having a release and blocking finger extendingtherefrom. Therefore, movement of the control knob that'renders theswitch open or closed also pivots the bellcrank and bellcrank finger.The bellcrank finger then contacts the link abutment and urges the linkto disengage from the fixed shelf.

Accordingly, an object of the present invention is to release thecarriage from the upper carriage shift position to the lower carriageshift position when the switch is conditioned to the open state. Thelower position of the carriage provides a low silhouette with noportions of the carriage projecting beyond the basic machine lines.

Another object of the present invention is to block the depression ofthe keylever when the switch is in the open state to prevent actuatingof the shift mechanism 2 until the switch is again conditioned in theclosed state by the control knobJThis sequence protects the drive motorby preventing the drive motor from being prematurely loaded by the shiftmechanism.

Other objects, features, and advantages of the invention will becomemore apparent from the following description, appended claims, andaccompanying draw- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a leftelevation view ofa typewriter showing the present invention with thecarriage in the lower case shift position.

FIG. 2 is a view similar to FIG. 1 except the keylever is depressed andthe carriage is in the upper case shift position.

FIG. 3 is an enlarged elevational view showing of the shift lock linkbeing released by the release mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings and inparticular to FIG. 1, a portion of a typewriter 10 is shown. A carriage12 provides the support for a printing platen 14. Carriage l2, movablefrom a lower shifted position to an upper shifted position, is shown inthe lower shifted position with a typebar 15 impacting on platen 14.

An electrically operative switch 16 is fixed to a frame member 18. Aswitch bellcrank 20 is pivotally supported about pivot 21 and is coupledto a switch button 22 of switch 16. Switch button 22 is responsive tothe pivotal movement of switch bellcrank 20 to condition switch '16 to aclosed state or an open state.

A control link 24 has one end 26 pivotally coupled to switch bellcrank20. Control link 24 extends forward and is pivotally connected to acontrol knob 28 at a pivot 30 that is spaced from either end of controllink 24. Control link 24 extends further forward and terminates in ahorizontal flange 32 that extends inward.

Control knob 28 is rotatable about a frame mounted stud 27 and ispositioned above control link 24 for easy access by an operator. Controlknob 28 includes a projecting abutment 29 and a projecting hub 31.Abutment 29 limits the counterclockwise rotation of the control knob 28and hub 31 limits the clockwise rotation of the control knob 28. e

A flange 32 of link 24 is pivotally and'slideably coupled to anupstanding arm 34 of a bellcrank 36. Arm 34 includes a slot 38 in whichflange 32 is slideably engaged. Bellcrank 36 is pivotally supported on aframe mounted pivot stud 40. Bellcrank 36 further includes a secondupstanding arm 42 that terminates in a forward extending finger 44.

A shift keylever 46 is pivotally supported on frame 18 at pivot 47 andbiased upward towards a rest position by a spring 48. One end of spring48 (not shown) is mounted to frame 18 and the other end 53 is attachedto an extension 49 of keylever 46. Upward and downward movement ofkeylever 46 is limited by a pair of integral extending fingers 50 and 52that abut a fixed shelf 54 positioned therebetween.

A shift lock link 56 is pivotally supported about a pivot 58 on shiftkeylever 46. Therefore, any movement of shift keylever 46 results in acorresponding movement of shift lock link 56. A spring 60 connectedbetween extension 62 of keylever 46 and extension 64 of shift lock link56 biases lock link 56 upward towards a rest position. The rest positionof lock link 56 is determined by a lock link lug 57 that abuts a loweredge 59 of keylever 46. Shift lock link 56 further includes adownstanding abutment 66 that lies in the pivot path of bellcrank finger44 and has a forward edge 68 adjacent an edge 70 of fixed shelf 54.Forward edge 68 of abutment 66 includes a latching recess 72 and alatching surface 74.

During operation, control knob 28 is manually rotated clockwise asviewed in FIG. 2. Link 24 is urged rearward to pivot switch bellcrank 20rearward until switch button 22 conditions switch 16 to a closed state.

The rearward movement of link 24 also urges bellcrank .36 to pivotcounterclockwise. Bellcrank finger 44 is therefore positioned out of thepath of abutment 66 to allow for the depression of shift lock link 56.

When a continuous shift operation is desired, shift lock link 56 isdepressed. Link abutment 66 is moved downward as surface 68 abuts andslides down along shelf edge 70 as shown in FIG. 1. Abutment 66continues to slide down along shelf edge 70 until recess 72 is inalignment with shelf edge 70 at which time latching surface 74 slidesunder and into latching engagement with shelf edge 70 as shown in FIG.2. At this time, through appropriate linkage (not shown), printingplaten 14 is conditioned to an upper carriage shift position.

When it is desired to discontinue the continuous shift operation. asviewed in FIGS. 1 and 3, keylever 46 is depressed. Lock link 56 is urgedto move downward until latching surface 74 is disengaged from shelf 70by the spring 60. Lock link 56 is then biased to pivot upward to itsrest position on keylever 46 by the spring 60 and keylever 46 is biasedto pivot upward to its rest position on frame 18 by the spring 48. Atthis time, carriage I2 is conditioned to a lower shift position.

if. however, the power supply of the typewriter is shut off withoutdisengaging the shift mechanism from its upper shift position, thepresent invention will become effective.

The present invention becomes effective when control knob 28 is manuallyrotated counterclockwise. Link 24 is urged forward until switchbellcrank 20 moves switch 22 to condition switch 16 to an open state.The forward movement of link 24 also urges bellcrank 36 to pivotclockwise. Bellcrank finger 44 is then pivoted into contact withabutment edge 68 as illustrated in FIG. 3. Continued pivotal movement ofbellcrank 36 progressively urges latching surface 74 to disengage fromshelf 70. Lock link 56 is then biased to pivot upward to its restposition on keylever 46 and keylever 46 is biased to pivot upward to itsrest position on frame 18. Carriage I2 is now conditioned to a lower:shift position and the typewriter is in an inoperative state.

A safeguard against actuation of the shift mechanism when the typewriteris in an inoperative state is provided for by the continued pivotalmovement of bellcrank 36. Continued pivotal movement of bellcrank 36positions bellcrank finger 44 under and into the operative path of locklink abutment 66. Therefore, any downward movement of lock link 56 isblocked until the control knob 28 is rotated clockwise and the con- 4trol link 24 pivots thc finger 44 from under the abutment 66.

What is claimed is:

l. A release mechanism for a power operated typewriter having a frame, aplaten supporting carriage shiftable on the frame between an upperposition and a lower position, a keylever operatively connected to thecarriage and supported on the frame for movement between a firstposition with the carriage in the lower position and a second positionwith the carriage in the upper position, an electrical switch operablebetween a closed state and an open state for energizing the typewriter,said release mechanism comprising:

locking means supported on the frame for locking the keylever in thesecond position;

control means supported on the frame for conditioning the electricalswitch between the closed state and the open state; and

means movably supported on the frame and responsive to said controlmeans for releasing the keylever from the second position for movementto the first position for locating the carriage in the lower position.

2. A release mechanism as defined in claim 1 wherein said locking meansincludes a lock link pivotally supported on said keylever, said locklink includes a latching shelf and an abutment, said locking meansfurther includes a shelf fixed to the frame for engagement by saidlatching shelf when the keylever is locked in the second position, andsaid responsive means includes a finger for contacting said abutment ofsaid lock link and moving said lock link for releasing said latchingshelf from said fixed shelf to release the keylever from the secondposition for movement to the first position for locating the carriage inthe lower position.

3. A release mechanism as defined in claim 2 wherein said lock linkincludes a lug for engaging the keylever to define an inoperativeposition of said lock link relative to the keylever, and a springconnected to said lock link for biasing said lock link to saidinoperative position when said lock link is released by said finger ofsaid responsive means.

4. A release mechanism as defined in claim 2 wherein said responsivemeans includes locking means located in the path of said lock link forpreventing depression of the keylever when said control means hasconditioned the electrical switch in said open state.

5. A release mechanism as defined in claim 4 wherein said blocking meansincludes a surface on said finger for underlying said abutment of saidlock link thereby preventing depression of the keylever.

6. A release mechanism as defined in claim 1 wherein said control meansincludes an operable member and a control link connected to saidoperable member, said control link couples said electrical switch tosaid responsive means for conditioning said electrical switch from theclosed state to the open state and for releasing the keylever from thesecond position for movement to the first position upon actuation of theoperable member.

1. A release mechanism for a power operated typewriter having a frame, aplaten supporting carriage shiftable on the frame between an upperposition and a lower position, a keylever operatively connected to thecarriage and supported on the frame for movement between a firstposition with the carriage in the lower position and a second positionwith the carriage in the upper position, an electrical switch operablebetween a closed state and an open state for energizing the typewriter,said release mechanism comprising: locking means supported on the framefor locking the keylever in the second position; control means supportedon the frame for conditioning the electrical switch between the closedstate and the open state; and means movably supported on the frame andresponsive to said control means for releasing the keylever from thesecond position for movement to the first position for locating thecarriage in the lower position.
 2. A release mechanism as defined inclaim 1 wherein said locking means includes a lock link pivotallysupported on said keylever, said lock link includes a latching shelf andan abutment, said locking means further includes a shelf fixed to theframe for engagement by said latching shelf when the keylever is lockedin the second position, and said responsive means includes a finger forcontacting said abutment of said lock link and moving said lock link forreleasing said latching shelf from said fixed shelf to release thekeylever from the second position for movement to the first position forlocating the carriage in the lower position.
 3. A release mechanism asdefined in claim 2 wherein said lock link includes a lug for engagingthe keylever to define an inoperative position of said lock linkrelative to the keylever, and a spring connected to said lock link forbiasing said lock link to said inoperative position when said lock linkis released by said finger of said responsive means.
 4. A releasemechanism as defined in claim 2 wherein said responsive means includeslocking means located in the path of said lock link for preventingdepression of the keylever when said control means has conditioned theelectrical switch in said open state.
 5. A release mechanism as definedin claim 4 wherein said blocking means includes a surface on said fingerfor underlying said abutment of said lock link thereby preventingdepression of the keylever.
 6. A release mechanism as defined in claim 1wherein said control means includes an operable member and a controllink connected to said operable member, said control link couples saidelectrical switch to said responsive means for conditioning saidelectrical switch from the closed state to the open state and forreleasing the keylever from the second position for movement to thefirst position upon actuation of the operable member.